There are known suspended ceilings which comprise a grid of elongate ceiling members, for instance Great Britian Pat. No. 1 472 285 describes one such ceiling. In such ceilings, the ceiling members can define one or more openings which are substantially larger than the normal spaces between the ceiling members, and which are closed by removable panels. Such openings can for instance provide access to the space above the ceiling. The panel can also comprise a grid of ceiling members and can be arranged such that the ends of the panel ceiling members butt or nearly butt against the sides of the ceiling members defining the margins of the opening, to provide visual continuity across the panel. In order to secure the panel in position, the ends of at least some of the panel ceiling members can have a detent piece; clips of roughly inverted-U shape are used to secure the ends of respective panel ceiling members to the sides of the margin ceiling members. In detail, each clip has a bridge portion which spans the margin ceiling member, means for limiting the downward movement of the clip with respect to the margin ceiling member (which means may form part of the bridge portion), jaws or retaining portions which extend down the sides of the margin ceiling member, at least the retaining portion on the side facing the panel ceiling member being sprung and passing down behind the detent piece in the end of the panel ceiling member, and a detent portion on the latter retaining portion for entering a detent in the detent piece in the end of the panel ceiling member and retaining the end of the panel ceiling member in position.
It is often specified that the panel should be demountable from below without having to raise the panel above the level of the ceiling. The use of the clips can achieve this, but may give various problems. The clips may not be captive, and can be pushed up off the margin ceiling member when the panel is raised into position. The clips do not necessarily give perfect alignment and if the panel is pushed up too hard in order to obtain alignment, the clip itself may rise or alternatively the panel may push up the surrounding parts of the ceiling and distort the whole ceiling. Lastly, due to a requirement which is frequently made that the panel can be dismounted without using any sort of tool, the detent portion which enters the detent in the end of the panel ceiling member may have an inclined upper surface so that the retaining portion and detent portion can be cammed aside when the panel is pulled down; this leads to difficulty in aligning the lower surface of the panel exactly with the plane of the ceiling; furthermore, small inaccuracies in tolerances can lead to the panel itself being easy to dislodge.
For convenience, the clips are described herein in the orientation they will assume when properly in position on the ceiling. However, it will be appreciated that they may be for instance manufactured, sold or stored in other orientations.